In order to produce squared lumber from a log, curved or wany edges of the log must be removed. To optimize the number of boards that can be obtained from the log, boards of optimum size are identified that will substantially fill the cross-sectional area of the log, leaving a number of such wany edges. In a process known as “profiling,” a cutting head (also known as a “profiling head”) is used to cut or chip away the wany edges, and this may be done before the boards are sawed from the log. Particularly, the cutting head cuts a corner that extends along the length of the log and that defines an outer side of one board and at least part of the upper or lower face of an adjacent board. To cut the corner, the cutting head rotates about an axis and has cutting surfaces oriented at right angles with respect to each other.
The cutting head has in the past typically included a knife for cutting the aforementioned upper or lower face in the example given above, the face defining a plane that is parallel to the axis of rotation of the cutting head (“facing cut”), and a saw for cutting the aforementioned outer side (“slicing cut”), which defines a plane that is perpendicular to the axis of rotation. More recently, cutting heads have been provided which employ knives for making both the slicing cut and the facing cut.
The speed of the profiling operation is increased if the wany edges for a number of boards can be removed by the same cutting head. A cutting head that can be used to cut away two wany edges at one time has at least one additional set of knives. The knives of the additional set are disposed a different radial distance from the axis of rotation than the first knives and are displaced axially therefrom as well.
For example, the first knives may be used to cut a first corner defined by an outer side of a first board and at least part of the upper face of a second board that lies beneath and extends laterally beyond the first board. The additional knives may simultaneously be used to cut an adjacent corner defined by an outer side of the second board and at least part of the upper face of a third board that lies beneath and extends laterally beyond the second board. The difference in radial positioning of the first knives relative to the additional knives, as well as the difference in axial positioning of the first knives relative to the additional knives, may define either the thickness of one of the boards or the difference in width between two adjacent boards. The absolute positioning of all of the knives of the cutting heads used to profile the log, in concert with the positioning of the cutting heads themselves, defines the dimensions of board lumber sawn from the log.
Examples of adjustable cutting heads are found in Dietz, Disclosure Document DE 44 19 324 (“Dietz”) and Linck, European Patent Application No. 96107714.6 (“Linck”). Dietz discloses an outer corner milling machine and an inner corner milling machine, each resembling a pot, one lying at least partially within the other. Each of the corner milling machines is adapted to cut a corner and is equipped for this purpose with a cleaver on the circumference surface and a plane blade oriented at right angles to the cleaver. “Adjustment units” are used to adjust the axial spacing between the two corner milling machines. The “adjustment units” are not described, but appear to be electric motors. Radial adjustment is not provided, and axial adjustment appears to require feed-back control of the motors to find and maintain a command spacing. This spacing can change as a result of the forces encountered by the milling machines and at least some time will be required for the controller and feedback mechanism to restore proper spacing, resulting in imprecise cutting.
Linck discloses a milling head having a large diameter ring of cleavers and a smaller diameter ring of cleavers. The cleavers have their cutting edges aligned with the axis of revolution of the milling head. The cleavers are attached to cleaver carriers which are fastened with screws to respective cleaver supports. The radial disposition of the cleaver supports can be adjusted by loosening the screws. The cleaver supports can also be moved in axial rails within the carriers and can be locked in at different axial positions with terminal blocks and screws. Disksaw segments are installed between the cleavers in the smaller ring. These are stated as being adjustable but no means for adjusting the disksaw segments is disclosed. Moreover, while the position of the cleavers can be adjusted both axially and radially, holding the cleavers in position depends on frictional forces exerted by tightening screws, so that there is no provision for positively locking the position of the cleavers.
Another problem with such cutting heads generally is that they are prone to load up with sawdust.
Accordingly, there is a need for an apparatus with adjustable saws for wood cutting that provides for the advantages inherent in the use of saw blades for cutting multiple corners in the wood, outstanding ease of adjustment and positive locking of the saws in their cutting positions, and resistance to the accumulation of sawdust, to minimize required maintenance and maximize the effectiveness of the wood cutting process.